FIG. 1 illustrates a data communication mode between two UEs in traditional cellular communication technologies. As illustrated in FIG. 1, voice, data, and other traffic of the two UEs are exchanged through evolved Node B's (eNBs) where the respective UEs reside, and a core network (an SGW/PGW).
A communication mode enabled in Device to Device (D2D) communication technologies is different from the communication mode illustrated in FIG. 1. As illustrated in FIG. 2, adjacent UEs can transmit data over a direct link in a short distance range by means of D2D without the data being forwarded through a central node (i.e., a base station). The D2D technology has the following advantages due to its short-distance communication characteristic and the direct communication mode:
(1) The UEs can communicate directly over a short distance to thereby achieve a higher data rate, a shorter delay, and lower power consumption;
(2) Spectrum resources can be utilized efficiently by the UEs widely distributed in the network due to the short distance characteristic of the D2D communication link;
(3) The direct communication mode of D2D can be adapted to a demand of e.g., wireless Peer to Peer (P2P) and other services, for sharing local data so as to provide a flexibly adaptive data service; and
(4) The large number of UEs widely distributed in the network can be utilized in direct communication of D2D to extent a coverage area of the network.
The LTE D2D technology refers to D2D discovery and communication procedures, controlled by an LTE network, operating in a Long Term Evolution (LTE) licensed frequency band. The LTE D2D technology can make full use of the original advantages of the D2D) technology, and some problems of the traditional D2D technology, e.g., uncontrollable interference, etc., can be overcome by the controlling LTE network. The introduction of the LTE D2D characteristic enables the LTE technology to evolve from the pure wireless mobile cellular communication technology toward the Universal Connectivity Technology (UCT).
The LTE D2D technology includes two aspects of a D2D discovery and D2D communication, where the D2D discovery refers to that a D2D User Equipment (UE) discovers another D2D UE nearby, and the D2D communication refers to that the D2D UE communicates data with the other D2D UE. A D2D signal can be sent or received in either of the discovery and the communication only if the UEs are synchronized to each other. In the coverage area of the network, synchronization reference (or referred to as a timing reference) can be provided by the base station, and all the UEs in the coverage area are provided with the synchronization reference according to a synchronization signal sent by the base station. Outside the coverage area of the network, a synchronization signal may be sent by a cluster head responsible for the synchronizing function provided by the base station so that the other UEs in a cluster can obtain the same synchronization reference according to the synchronization signal.
FIG. 3 to FIG. 5 illustrate three D2D transmission scenarios, where FIG. 3 illustrates a D2D transmission mode in a scenario of being covered by a network, FIG. 4 illustrates a D2D) transmission mode in a scenario of being not covered by a network, and FIG. 5 illustrates a D2D transmission mode in a scenario of being partially covered by a network. As can be apparent from FIG. 3 to FIG. 5, the D2D UE in any one of the scenarios may receive D2D signals sent by UEs from a plurality of cells or a plurality of clusters, so the respective D2D signals may be received according to D2D) transmission timings and D2D) resource configurations of the cells or the clusters where these UEs are located. Before this, the UE needs to firstly obtain synchronization references and D2D resource configuration information corresponding to the D2D signals of the different cells or clusters, where the resource configuration information of the serving cells or the clusters where the UEs are located can be indicated by base stations or cluster heads.
The D2D resource configuration information of the present cell is typically signaled by the base station, but there has been absent so far a method for enabling the UE to obtain the D2D resource configuration information of the other cells or the other clusters. Thus, for example, if the UE is not covered by the network, and the cluster head is incapable of allocating a resource, then the cluster cannot allocate or signal any resource, and only a fixed resource may be applicable to the UE, so that the same D2D resources may be used among the clusters, thus easily resulting in mutual interference.
There has been absent so far a working solution to the problem in the prior art of degrading the efficiency and quality of transmission by the UE of a D2D signal over a fixed resource.